The present disclosure relates to a method for producing a shock absorbing member for a sole of a shoe.
A shock absorbing member known in the art for a sole of a shoe is disclosed, for example, in U.S. Pat. No. 8,146,270. The shock absorbing member includes: a pair of walls spaced fore and aft from each other and elastically deformable in a fore-aft direction of a shoe by external force in a vertical direction; and a spring member elastically deformable and connecting together the pair of walls provided fore and aft (see FIG. 5B). Each of the walls has a substantially center portion in a vertical direction formed to curve and protrude toward the front or the rear of the shoe. Moreover, each wall has an interior wall face provided with a recess in a substantial center of the interior wall face in the vertical direction. The recess extends in the foot width direction of the shoe. Furthermore, the spring member is shaped into a flat plate so that each of a front end and a rear end, of the spring member, shaped in a substantially oval shape in cross-section fits into a corresponding one of the recesses on the walls, and stretches fore and aft.
In the shock absorbing member cited in U.S. Pat. No. 8,146,270, each of the walls elastically deforms by external force in the vertical direction, and, in response to the elastic deformation of each wall, the substantially center portion of the wall in the vertical direction moves toward the fore-aft direction of the shoe. Simultaneously, the spring member is pulled fore and aft while both ends of the spring member fit into the recesses, and elastically deforms. Meanwhile, when the external force in the vertical direction disappears, resilience of each of the walls and spring member causes the shock absorbing member to return to the original state. This exerts shock absorbing properties and repulsive force.
However, the ends of the spring member merely fit into the recesses of the walls. Hence, when the walls elastically deform significantly by relatively large external force, the spring member excessively stretches. As a result, both ends of the spring member might inevitably come off the recesses of the walls. Specifically, it would be difficult to stably hold the spring member against the walls. The shock absorbing member cited in U.S. Pat. No. 8,146,270 requires an operation to separately assemble each of the walls and the spring member. Such an operation makes it difficult to produce a robust shock absorbing member.